Regional Blood Flows by the Microsphere Method: Reproducibility in Portal Hypertensive Rats and Influence of a Portal Vein Catheter

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Abstract
To determine the reproducibility of splanchnic blood flow measurements by the microsphere method in rats with portal hypertension and the effects of laparotomy with portal vein cannulation, eight groups of 10 rats were studied. Cardiac output and regional blood flows were measured twice, 10 min apart, in pentobarbital anesthetized or awake, sham-operated or portal vein-ligated rats, with or without portal cannulation. Variability between the two successive measurements was not affected by portal hypertension or portal cannulation, and was not different in the splanchnic territory and in other organs. Laparotomy with portal cannulation had no significant effect in sham-operated rats. In awake portal hypertensive rats, cardiac output (53.9 ± 3.0 vs 45.8 ±2.9 ml · min-1 · 100 g body wt-l, P < 0.01) and splanchnic blood flow (12.31 ± 0.72 vs 9.34 ± 0.85 ml · min-1 · 100 g body wt-1, P < 0.01) were lower in portal vein cannulated rats compared with those of non-cannulated animals. In anesthetized portal hypertensive rats blood flows were unaffected by portal cannulation, but arterial pressure (100.2 ± 4.3 vs 119.9 ± 3.4 mm Hg, P < 0.01) and heart rate (366.5 ± 10.0 vs 405.5 ± 7.4 beats · min-1, P < 0.01) were elevated. Anesthesia also decreased portal pressure (14.8 ± 0.5 vs 12.0 ± 0.4 mm Hg, P < 0.05) in portal hypertensive rats. We conclude that the microsphere method remains reproducible in portal hypertensive rat models. Laparotomy with portal cannulation can alter systemic and splanchnic hemodynamics in portal hypertensive rats; these effects can also be changed during pentobarbital anesthesia. Regional blood flow measurements in portal hypertensive rats should be performed in animals without portal cannulation and preferably in the awake state.

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